Control mechanism for steam heating systems



Dec. 3, 1940. c JENNINGS 2,223,689

CONTROL MECHANISM FOR STEAM HEATING SYSTEMS Filed Nov. 24, 1934 8Sheets-Sheet 1 Dec. 3, 1940. 1. c; JENNINGS 2.2235

CONTROL MECHANISM FOR STEAM HEATING SYSTEMS Filed Nov. 24, 1934 8Sheets-Sheet 5 .Zhven for IC "By W W Fffo rn 9.5

Dec. 3, 1940. 1. c. JENNINGS 2 ,6

CONTROL MECHANISM FOR STEAM HEATING SYSTEMS Filed Nov. 24, 1934 8Sheets-Sheet 4 I Q 1 Of if M i Q Q Diar orgi IcfwH/HGS By W 567 Dec. 3,1940. I. c. JENNINGS CONTROL MECHANISM FOR STEAM HEATING SYSTEMS FiledNov. 24, 1954 8 Sheets-Sheet s gvwewtow ICJnni/ res,

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CONTROL MECHANISM FOR STEAM HEATING SYSTEMS Filed Nov. 24, 1934 8Sheets-Sheet 8 jg @V/ Patented Dec. 3, 1940 UNITED STATES PATENT OFFICEamass I con'raor. I sort s'rssu ammo srs'rmss Irving 0. Jennings, SmithNorwalk, Conn.

Application November 24. 1934, Serial No. 154,674

ltclailns.

This invention relates to a control mechanism for a steam heating systemand particularly for a vacuum steam heating system.

A vacuum steam heating system consists of a source of steam supplyconnectedto the radiators and a pumping mechanism connected to thereturns from the radiators. This pumping mechanism consists of a tankconnected so that the air and gas in the returns will be separated andpumped out of the system and so as to create a vacuum, that is apressure below atmospheric pressure, in the returns. A water pump isalso usually employed to remove the water of condensation and generallyto return the same to the boiler.

The improved control mechanism consists of a steam valve placed in thesteam supply, which ing provided to supply a decreased pressure ofsteam.

The increase and decrease controllers are connected to and operated bythe pressures in the pipe leading steam from the steam valve to theradiators and these cosltrollers operate switches which, as selected bythermostats, control the operation oi the electric motor operating thesteam valve.

Two vacuum controllers are provided to throw the vacuum pump into andout of operation to produce either one of a plurality of vacuums in thereturns of the system or sometimes to cut the vacuum pump entirely outof operation.

The parts are so arranged and combined, that, first, normally the steamvalve will be partly opened to allow a throttled supply of steam under alow pressure to pass to the radiators and so that the vacuum pump isoperated and controlled to produce a high vacuum; second, so thatiitheareatobeheatedbecomestoocooLthe steam valve will be opened wider togive a highm er pressure oi. steam and the vacuum pump will becontrolled and operated topmduce a low vacuum in the returns; and,third, so that i! the area to be heated'becomes too hot, the steam valvewill be closed but the vacuum pump will a6 continue to operate so thatthere will be full vacuum available for circulation as soon as the areato be heated returns to normal temperature.

In some instances when the steam valve is closed, the vacuum controllermay be set so that l the vacuum pump will be cut entirely out ofoperation.

In some installations, the building to be heated may be zoned andadditional thermostatically controlled shut of! valves may be employedso 1 that steam can be cut ofl from any particular zone it it gets toohot.

By these arrangements steam can be very economically used and thebuilding or area to be heated can be kept accurately at a uniformtemperature. a

The invention is illustrated in the accompanying eight sheets ofdrawings, referring to which:

Fig. 1 is a diagrammatic elevation illustratins the application of myinvention to a vacuum steam heating system.

Fig. 1a is a diagram illustrating the electrical connections used in theapparatus shown in Fig. 1.

Fig. 2 is a view similar to Fig. 1 illustrating a 25 further carryingout of my invention, showing how the same can be connected to controlthe temperature in a plurality of zones.

Fig. 2b is a wiring diagram showing the elecso trical connections usedin the apparatus shown in Fig. 2.

Fig. .2c is an additional diagram showing the wiring to the additionalzone shut-oi! valves.

Fig. 3 is a sectional elevation illustrating the 85 steam valve and themechanism employed to open, close or hold the same in intermediateposition.

Fig. 4 is a partial central sectional elevation at right angles to rig.8. 0

Figs. 5 and 6 are detail views showing the cut out or limit switchesemployed in connection with the electric motor.

Fig.7is aplanview.andl"ig.8acentralsectional elevation of the steamincrease supply 5 controller.

Fig. 9 is a cross sectional plan view on the line H of Pig. 8.

Fig. 10 is a central sectional elevation on the line li-l. oi 1"ig. 8.50

modification by which both supply controllers aremade as a unitstructure.

Fig. is a front elevation of one of ther mostats employed. I

Fig. 16 is a similar view with the front cover thereof taken off, and YFig. 17 is a cross sectional elevation showing the contacts used in thethermostat.

Referring to the drawings and in detail, A designates a steam boiler,extending from which is a steam pipe B, in which is arranged anautomatically operating pressure regulator C. This regulator C maybeadjusted so that the pressure in the steam pipe beyond the regulator-Cmay be kept constant, say at five pounds. A motorized steam valve D isarranged in the steam pipe beyond the pressure regulator C, and the pipeE beyond the valve D constitutes the supply pipe for the heating systemor radiators F.

The radiators F are supplied with the usual valves and traps and areconnected by pipes to a return G, which is connected to the receivingtank H of the pumping mechanism. a

This pumping mechanism, as shown, consists of a well known unit.comprising a Nash vacuum pump for creating and maintaining a vacuum inthe returns G and a centrifugal impeller for removing the water ofcondensation, and preferably I operation by a float J arranged inthetank H operating a switch K; and also by one or the other of a pluralityof vacuum pump controllers L and M.

The details of this vacuum pumping mechanism are well known and areshown and de-- scribed for instance in Letters Patent of the UnitedStates, No. 1,592,024, granted to me July 13, 1926.

The foregoing, with the exception of the employment of a plurality ofvacuum pump controllers, comprises the main or principal elements of awell known vacuum steam'heating system,

by which steam under a vacuum, that is under a pressure below that ofthe atmosphere, can be circulated and employed to heat an area orbuilding.

The details of the motorised steam valve D, shown in Figures 3 and 4 ofthe drawings, will now be described.

The same consists of a valve Ill cooperating with a valve seat II. Thevalve III is arranged on a stem l2, which is connected by a yieldingjoint I! to a secondary stem l4 carrying a rack I. An electric motor IIis connected by a triple train of reducing gearing to drive a shaft l1carrying a pinion ll meshing with the rack It. The shaft I1 is providedwith cams lQ-Ili to break the electrical connections to the motor, whenthevalve is moved to its extreme open or closed position, and thusacting as limiting switches so that when the valve is fully open orclosed, the motor will stop.

The yielding joint I3 is provided so'that when the valve is closed, themotor I! will not come up against a dead stop.

' By this arrangement, the valve can be opened, closed or moved to anintermediate position.

The details of the steam increase controller X, shown in Figs. 7 to 10,inclusive, will now be described. The same consists of a casing II inwhich is arranged a diaphragm II. The space in aaaaeso the casingbelowthediaphrasm is connected by apipelitothssteamsupp rp p lertendingfrom the motorized valve D. A rod or plunger 24 is connectedto thediaphragm 22. The top end of the rod "is fitted in a yoke or bracket II.A spring is arranged between the bracket II and a nut 21 adiustablythreaded on the rod 24. A' pivoted bell crank lever ll extends betweencollars II and 29' secured on the rod 24. The upper end of the bellcrank lever 2| is pivoted to an arm 10 depending from a shaft 8|journalled in arms extending upwardly from the bracket 25. Clamps 82-42are secured on shaft 3i and mercoid electric switches Nand N are held inthese clamps. a 7

By the electrical connections hereinafter described, these mercoidswitches N and N control the opening and closing operation of theelectric motor I, which operates the steam valve D.

It will be noted that by turning the nut 21, the pressure below thediaphragm 22 necessary to rock the mercoid switches N and N can beadiusted and determined.

The details "of the steam decrease controller Y shown in Figs. 11 and 12will now be described. The same consists of a casing II in which isarranged a diaphragm M. The space in the casing below the diaphragm isconnected to the pipe 23 extending from the steam supply pipe E. A rodor plunger 85 is connected to the diaphragm 34. The top end of the rodis fitted in a yoke or bracket 38. A spring 31 is arranged between thecollar 40 abutting on casing 33 and a nut 38 adiustably threaded on therod 35. A pivoted bell crank lever 39 extends between collars 40' and40" secured on the rod 35. The upper end of the bell crank lever 38 ispivoted to an arm ll depending from a shaft 42 journalled in armsextending upwardly from the bracket 38. Clamps 43-43 are secured on theshaft 42 and mercoid electric switches 0' and 0 are held in theseclamps. By the electrical connections hereinafter described thesemercoid switches 0' and O control the opening and closing operation ofthe electric motor I.

The vacuum pump controllers are ordinary vacuum switches set to close acircuit until a certain adjusted vacuum is reached and then to open thecircuit.

In the apparatus being described, the vacuum pump controller M is set topermit the creation and maintenance of a vacuum of twenty-three inchesin the returns before cutting out, and the low vacuum pump controller Lis set to cut out at five inches of vacuum.

The steam decrease controller Y last described is, substantially thesame as the steam increase controller x previously described, exceptthat the spring 31 is set to oppose the downward movement of thediaphragm ll, while the spring 2| used in the steam increase controlleris set to oppose the upward movement of the diaphragm Thus the operationof the steam increase controller is the same as the steam decreasecontroller Y except that in the steam increase controller X, thediaphragm moves upwardly against an adjusted spring pressure, while inthe steam decrease controller Y, the diaphragm moves downwardly againstan adjusted spring pressure.

In some instances, I contemplate making the steam increase controller 2:and the steam decrease controller Y as a'unit structure, as shown inFigs.13 and 14. In this arrangement the springs 20 and 31 are arrangedon a common asaaese the magnetic switching arraneement, and

rod 2|'8l' and only one diaphragm iT-N' is employed in the casing2l'--l8'. The rod 20-3 carries a rack ll, whichmedsea with apinlonllsecuredonshaftllcarryingallthe mercoid switches.

Inthediagrammaticl'lguresiandlandin the diagrams of the electric wiring.Figs. 1a and.

2b, double pole mercoid switches are shown for the purposes ofexplanation, but in actual practice, two single pole mercoid switchesare employed both in the steam increase controller x and in the steamdecrease controller Y.

The apparatus is thermostatically controlled.

A plurality of thermostats 1- may be employed and connected electricallyin multiple so that the control may come from diii'erent key positionsin the building.

.One of the thermostats is shown in Figs. 15,. 16 and 17 of the drawinssEach thermostat is preferably made double or duplex having athermostatic arm I cooperating with two contacts 40 and u, and a secondthermostatic arm ll cooperating with two contacts Ii and I2. The partsII, II and II are arranged in one control circuit, which is used forcontrolling the temperature in the daytime, or normally, and the partsIO, Ii and I! are arranged in another control circuit which is employedin the night time and holidays, when the building can be kept at a lowertemperature to save steam.

A time clock Q preferably is used to shift the control automaticallyfrom one circuit to the other.

A relay box R is set at any convenient position and the electricalconnections extend to and from the same. This relay box contains tworelays S and S and a transformer T.

The electrical energy for the control maybe taken from an ordinarysingle phase 110 volt A. C. circuit, which is stepped down through thetransformer T, so that the current employed in the thermostats may be oflow voltage. rent employed to drive the motor I may be 220 volt threephase A. C., which is connected to a magnetic starter U.

The adjustments may be such as to maintain a day temperature of normally71 degrees, withing limits of 70 and 72 degrees, and the adjustments fornight temperature may be such as to maintain a temperature of 61 degreeswithin limits of 60 and 62 degrees Fahrenheit.

U indicates a commercial type of magnetic starter controlled by the highvacuum controller or regulator M, the low vacuum controller L and floatswitch K connected to the pilot circuit.

As the condensate collects in receiver tank H of Fig. i, the floatswitch K is closed by ball float J at a predetermined level and currentflows from one line terminal in motor starter U, Fig. in,

along lines 806-801 through closed contacts of float switch K. alonglines 30H, through the pilot magnetic circuit of starter U to the otherside, of one phase, thus energizing the magnetic switching mechanism andthrough lines 303-404-305, operating motor I and air and water pump,lowering the condensate level until ball float J opens float switchcontacts.

To maintain the desired vacuum condition, say 20" vacuum steam, acurrent flows from one line terminal in motor starter U, along linesMil-Ill, through closed contacts of vacuum regulator M, along lines lil,through closed contacts HM of relay 8, along lines Ill, 308, through themagnetic circuit of starter U to the other side of one phase, thusenergizing The curtorlfdrivingthe'airandwaterpunp,therebylncreasingthsvamumtomy33"whenthevacuumregulatorlopenainterrimtingthsmag- 5'neticcircuitofstartermthiustoppingthemotor Iandpump.Asthevawumleveldropstosay 21" the vacuum switch I again closes and aboveoperation is repeated.

Whe'ntheareatobeheatedbecomanifllcientlycoldtodemandsayl#pressuresteam,relayS is actuated by the thermostat circuit and contacts Ill-ill are opened,thus disconnecting highvacuumregulatorllfromservice. Duetovacuumregulatorhbeingsettooperateatsaye" it will now become eiiective tomaintain a 5" vacuum on return lines with i# pressure steam on supp y-The operation is as follows, referring first to thedayoperation:

Theterminchesofvacuum"isusedhereafter to refer to the pressure belowthat of the atmosphere, measured by a mercury column, two inches of suchcolumn substantially equalling a pressure ofonepound.

Referring to Figs. 1 and iapthe thermostatsareallshowninthemiddlemeitionfordayoperstlon. The normal temperature of71 degrees vacuum pump controller it has um pump to create and maintaina twenty three'inchesinthereturnsfl. Thiswill as give a diflerential'ofthree inches the sufiply'E-and the returns a from the and willprovide for a smoothxand economical, steam circulation, giving an even.mild heat in the radiators.

lfthesteamattwentyinchesofvacuumand this differential of three inches isnot suflicient to maintain the temperature oi 71 degrees in thebuilding, and the same drops to- 70 degrees, one of the thermostatcontrolling arms '41 will move over to one of the contacts marked ll,Fig. 1a, which will throw in the circuit which energizes the magnet ofthe relay 8, and cause contact to be made in the relay in the pointmarked 10, Fig. 1a. This disconnects the mercoids oi the steam decreasecontroller Y and connects the mercoids of the steam increase controllerx which now closes the circuit operating to open the valve D until thesteam pressure rises to one pound in the supply pipeE. This pres- 55sure will move the steam increase controller until its mercoids N and Nare level and so that the circuits controlled by the same are broken.

The steam pressure now remains constant at one pound until the buildingis brought up to the proper temperature, say 71 degrees, when thecircuit in the thermostat is opened and the valve D is returned to thetwenty inch setting for normal operation.

During this operation, with one pound pressure in the supply pipe E, thevacuum pump controller M is disconnected, and the vacuum pump controllerL is connected which allows the vacuum pump to create and maintain avacuum of live inches. This pound pressure in the supply and five inchesvacuum in thereturns gives a working differential of about seven inches,which will cause the steam to circulate more rapidly to quickly bringthe pressure in the radiators up to the higher pressure of one pound.

4 v I assaoso when the me to be heated'is brought up to .normaltemperature '71 degrees. the parts will return to the position shown inFigs. 1 and 1a to work on the twenty three inches vacuum and three inchdiflerential, before described.

When the building becomes too hot, a thermostat arm closes a contact It,Fig. 1a. The relay 8' is energized and the electric motor I0 is operatedto move the valve II o! the motorized steam valve D to its seat II.This-will shut oi! the passage of steam to the heating system orradiators. Under this condition the heating system will be cut entirelyout of operation, and there will be no circulation in the radiators.

This condition will continue until the too hot area returns to normaltemperature, when the parts will return to the positions for normaloperation, as shown in Figs. 1 and 1a.

Speciiic examples or conditions of operation are as follows. First,assume an inside temperature of 70 F., or below, with the time switch Zin day or high level position, and all other conditions as shown, wehave a situation which might be termed a 1# pressure steam position.

Current now flows from low voltage transformer T, along line 200,through the (1 contacts of time switch Q, along lines 20I--202, throughclosed 70 contacts of thermostat P and P along lines 200-204-205,through electro-magnet of relay S, along lines 200201 to complete lowvoltage circuit and to energize the electromagnetot relay S, causing itscontact-carrying armature to move against the magnetized core, thusclosing contacts IIO-I0| and opening contacts I00-I01, also openingcontacts 020-3. Current now flows from 110 v. supply along I00-IOI,through line switch Y, along I02--I03, through motor I0 and neldOP,through closed contacts of limit switch L0, along line I" through closedcontacts 01' mercury switch N of steam increase pressure selector x ofFig. 1 along line II8, through closed contacts I01 and H0 of relay S,along line I00 through closed contacts I09--I I0 of relay S, along linesI I II I2, through line switch Y, along lines Ill and Ill, completingcircuit and energizing motor I0, causing valve D 01' Fig. 1 to open,admitting pressure steam to supply line E. As thevalve D, Fig. 1,reaches full open position, the cam II, identical to 20, Figs. 5 and 6,contacts limit switch LO, interrupting the circuit and de-energizingmotor I0. As the relay S also opens contacts 320 and "I, thusdiscontinuing high vacuum regulator M, placing the low vacuum regulatorL in control of motor and pump I and Ip, the vacuum in supply line E nowrapidly decreases toward zero and pressure builds up to 1#. The pressureselector X of Fig. 1, through its mechanism actuated by pressure in pipe28, moves the mercury switches N and N until say at 1%#, mercury switchN is open and N is closed, causing current to flow from 110 v. supplyalong I00-IOI through line switch Y', along lines I02-l0l, through motorI. and field CL. through closed contacts of limit switch LC, along linesIll-I II, through closed contacts of mercury switch N, along lines III,through contacts Iii-I01 of relay S,. along line Ill, through contactsI00I I0 of relay 5', along lines III-III, through line switch Y, alonglines III-Ill, completing the circuit, energizing motor I0 and movingvalve D,

Fig. 1, toward closed position, thus, by throttling, reducing thepressure in line it and also in pipe As the pressure falls, the steam.increase presatsay1#bothN andN'areopen-circuitedand the valve is held inthis position until a variation in. pressure causes the closing ofeither N or N, thus causing motor I 0 to operate and valve D to open orclose as required to maintain 1# pressure steam in line E and pipe 20. I

Low vacuum regulator L maintains a minimum otsay 5" on return line G,Fig. 1.

For a different condition, we might assume minside temperature 0! ,71'F.', with time switch Q in day or high level condition, as shown, thisbeing what might be termed a 20" vacuum steam p sition.

No current flows in the low voltage transformer circuit. Current flows:Irom the 110 v. supply lead I00, along line IOI, through line'switch Y,along I02, I00, through motor II and held CL, through closed contacts orlimit switch LC, along line I04 through closed. contacts of mercuryswitch 0', along line III, through closed contacts I00-I01 of relay 8,along line I 00, through closed contacts I00-H0 of relay 3', along linesIII-I I2, through line switch Y, along lines III .and Ill to completecircuit, energizing motor I0, causing valve D, Fig. 1, to close in steamsupply line E. As valve D seats, cam 20, Fig. 8, contacts limit switchLC, causing it to interrupt the motor circuit and position the valve atfull closed.

As the vacuum in supply line E rises due to the operation of the vacuumheating pump 1 as heretoiore described, the vacuum selector Y of Fig. 1is actuated through pipe line 23 and via its mechanism moves the mercuryswitches O and 0 until say at 21" a position has been reached at whichmercury switch 0 is open-circuited and O is closed, establishing acircuit and current flow from 110 v. supply lead I00 along line IOI,through one side or line switch Y, along lines I02-I03, through motor I0and field 0 through closed contacts of limit switch LO, along line IIIthrough closed contacts oi mercury switch 0', along line I05,.throughclosed contacts I00-I01 of relay 8, along line I00, through closedcontacts I00-I I0 of relay 8', along lines III-I I! through line switchY", along lines II3I I l, completing circuit and energizing motor l6,causing valve D, Fig. 1, to move toward the open position, admittingpressure steam tosupply line E, thus reducing the vacuum to say 20", atwhich point the mechanism of vacuum selector Y, Fig. 1, has retractedthe mercury switches 0 and O to a horizontal position, where bothswitches are open-circuited, thus de-energizing motor I0 and positioningvalve D, Fig. 1, in a partly open condition suitable to maintain 20"vacuum steam.

As the steam supply pressure or the vacuum supply pressure changes, thebalance of vacuum selector Y, Fig. 1, is upset and operates immediatelyvia mercury switch 0 it below say 19", and mercury switch 0' it above21", to reestablish 20" condition by adjusting the valve opening.

High vacuum regulator M maintains a minimum vacuum 0! approximately 23".

If we now assumean inside temperature of 72 F., or over, with the timeswitch in day position, and all other conditions as shown, we havecontacts of time switch Q, along lines 20L 202, through '72 contacts oithermostat P along line 2| I, through 72 contacts of thermostat P alonglines 2l0, 200, through electro-m et of relay 5', along line 200 and201, completing the circuit and energizing relay 8', causing thecontact-carrying armature to move against the magnetized core, openingcontacts l09-l l0 and closin8contactsH0andI22.

Current now flows from v. supply along lines I00I0l, through line switchY, along lines l02i00, through motor I and field CL, through limitswitch LC contacts along lines l2l, I20, through closed contacts|l0--I22 of relay S, along lines |Il-Il2, through line switch Y, alonglines ll3-l ll, to complete the circuit, energizing motor I. and causingvalve D, Fig. 1, to move toward iull closed position, at which pointlimit switch LC is tripped by cam 20 of Figs. 5 and 6, de-energizingmotor l6 and positioning the valve at full closed. Inasmuch as relay Sis in normal or de-energized position, maintaining contacts 320-02|closed, the pump and motor control is by regulator M and a minimumvacuum of approximately 23" is maintained in line E.

Vaccum selector Y is operated by the high vacuum but is not in circuitand not efiective.

Applying the first condition or situation in which we have a 1# pressuresteam position, but for night level conditions, it might be assumed thatthe time switch Q is in its night or low level position, and thetemperature is 58, or lower, all other conditions as shown.

Current now flows from the low voltage transformer T along line 200,through the 11. contacts of time switch Q, along line 2, through the .1contacts of emergency switch Z, along line 0-216, through the closed 58contacts of thermostats P and/or P along lines 2 I |2l8- 205, throughelectro-magnet of relay S, along lines 206-201, completing circuit.

The sequence of operation now is exactly as described for condition 1,supra.

With time switch Q in night level position, the 20" vacuum steamcondition will similarly duplicate condition 2.

With time switch Q in night level position, the shut-oil condition willsimilarly duplicate condition 3.

With reference to the night level, 1# pressure steam position, asdescribed, with a demand continuous for high level temperature for aperiod of several hours, within the normal low level time period, theemergency or manual switch Z may be changed from contact position n tocontact position d, and then it will be noted that the normal nightlevel of l# pressure steam position has been changed to the firstcondition outlined above, with the emergency or manual switch Z in dayor high level position. This condition will remain until the manualswitch Z is again re stored to contact position n. The 20" vacuum steam,and the shut of! positions are equally and similarly aflected.

Thus, there are several conditions of operations, including normalheating under vacuum with a small differential for normal operation, aheating with higher pressure steam, and a low vacuum in return line Gwith a larger differential when the building becomes too cool, ashutting off of the steam, stopping circulation in the radiators whenthe building becomes too hot, and various incidental conditions such asnight level, or emergency conditions.

When the supply of steam is entirely shut oi! by the closing 0! thesteam valve D, the vacuum pump controller M may be left in operation, sothat when the main steam valve D is again opened there will be a quickcirculation and refilling oi the radiators.

In other instances, particularly in warm weather, the vacuum pumpcontrollers may be so arranged that the vacuum pump will be entirely outout of operation so long as the steam valve D is closed. thus savingelectric current.

In some cases the increase controller X may be omitted. When this isdone the reducin valve C is set for the maximum pressure at which thesystem is to be operated, and the valve D, under control of thethermostats, is arranged to open wide for increased heat, is partlyopened by the decrease controller Y ior normal heat, and is shut oil toprevent overheating, the same as in the arrangement already described.

When orifices or restrictions on the supply pipes to the radiators areused, it may be possible to operate the vacuum pump on low vacuum only,or in some cases the vacuum pump may be dispensed with entirely and thesystem operated above atmospheric pressure.

of course, at all times the pump is under the control 01' the float Jand switch K, and will operate to return the water of condensation tothe boiler, whenever this is necessary by the filling up 01! the tank H,irrespective of how the pressures and vacuums in the system areadjusted.

Referring now to the modification shown in Figs. 2, 2b and 20, it willbe noticed that the main steam supply E beyond the steam valve D isdivided into a plurality of sections as E and E2 and that additionalshut ofl valves D and D2 are put in these branches. D and D2 areoperated by electric motors and controlled by thermostats P and P2. Thepipes E and E2 extend to heat difierent zones in the building.

Thus when a thermostat cuts over to a too hot position (72) instead 01'shutting oil? the main control valve D, the thermostat will close itsrespective zone valve, D or D2. Otherwise the operation is the same asdescribed in connection with the apparatus illustrated in Figs. 1 and1a.

The pressures and vacuums herein referred to describing the operation ofthe apparatus are merely for illustration and, of course, variousadjustments in pressure and vacuums can be made to adapt the apparatusfor use in various buildings.

The details and arrangement herein shown and described may be greatlyvaried by a skilled mechanic without departing from the scope of myinvention as expressed in the claims.

Having thus fully described my invention, what I claim and desire tosecure by Letters Patent is:

1. A control mechanism for a steam heating system comprising a steamsupply pipe, a regulating valve in the steam supply pipe, automaticallyoperating mechanism including a steam increase controller, and a steamdecrease controller, connected to said supply pipe, electric meanscontrolled thereby, for adjusting said valve to maintain insaid system ahigh pressure, or a lower pressure, or to shut oil the steam, andthermostatic control means for said automatically operating mechanism.

2. A control mechanism for a vacuum steam These valves I heating systemcomprising a steam supply pipe,

a regulating valve in the steamsupply pipe, automatically operatingmechanism including a steam increase controller, and a steam decreasecontroller, connected to said supply pipe, electric means controlledthereby, for adjusting said valve to maintain in said system a highpressure, or a lower pressure, or to shut oi! the steam, andthermostatic control means for said automatically operating mechanism,and a vacuum pump for creating and maintaining a vacuum in the returns.

3. A control mechanism for a vacuum steam heating system comprising asteam supply pipe, a regulating valve in the steam supply pipe,.automatically operating mechanism including a steam increase controller,and a steam decrease controller, connected to said supply pipe, electricmeans controlled thereby, for adjusting said valve to maintain in saidsystem a high pressure, or a lower pressure, or to shut off the steam,thermostatic control means for said automatically operating mechanism, avacuum pump i'or creating and maintaining a vacuum in the returns, andcontrollers for the pump connect- .ed so that the pump willautomaticallybe set to create difierent vacuums to co-operate with thedifferent steam pressures.

4. A- control mechanism for a vacuum steam heating system, comprising asteam supply pipe, a regulating valve in the steam supply pipe,automatically operable mechanism including a same to open the valve,when' more steam is needed, and to close the valve when less steam isneeded, thereby vto maintain a determined temperature, a two-step vacuumcontrol for the vacuum pump so connected that when the system is on lowsteam pressure the pump will operate to create and maintain a relativelyhigh vacuum, and when the system is on high steam pressure the pump willoperate to create and maintain a relatively low vacuum. 1

5. A control mechanism for a vacuum steam heating system, comprising asteam supply pipe, a regulating valve in the steam. supply pipe,automatically operable mechanism including steam increase and decreasecontrollers connected to said supply pipe, electric means controlledthereby, for automatically adjusting said valve, a vac--.

uum pump for creating and maintaining a vacuum in the returns,thermostats connected to the valve operating mechanism to cause the sameto open the valve when more steam is needed, and to close the valve whenless steam is needed, thereby to maintain a determined temperature, aplurality of vacuum controllers for the vacuum pump so connected thatwhen the valve is partly opened, the pump will operate to create andmaintain a relatively high vacuum, and when the valve is opened for ahigher steam pressure. the pump will operate to create and maintain arelatively lower vacuum, and when the valve is closed, the pump willcontinue to maintain the relatively high vacuum.

6. A control mechanism for a vacuum steam heating system having a steamsupply, radiation means, a supply pipe to said radiation means andreturns from said means, comprising a regulating valve in the steamsupply pipe,

mechanism for automatically adjusting said valve, a vacuum pump forcreating and maintaining a vacuum in the returns, a plurality of vacuumcontrollers for the vacuum pump, a steam increase controller and a steamdecrease controller, connected to said steam supply pipe, electric meanscontrolled by said steam increase and decrease controllers to operatesaid valve, and thermostats selectively connected to the increase anddecrease controllers to control the temperature as described.

7. A control mechanism for a vacuum steam heating system having a steamsupply, radiation means, a supply pipe to said radiation means andreturns from said means, comprising a regulating valve in the steamsupply pipe, mechanism for automatically adjusting said valve, a vacuumpump for creating and maintaining a vacuum in the returns, a pluralityof vacuum controllers for the vacuum pump, connected to a return, asteam increase controller and a steam decrease controller connected tothe steam supply pipe beyond the regulating valve, electric meanscontrolled by said steam increase and decrease controllers to operatesaid valve, and thermostats selectively connected to the increase anddecrease controllers to control the temperature as described.

8. A control mechanism for a vacuum steam heating system having a steamsupply, radiation means, a supply pipe to said radiation means andreturns from said means, comprising a regulating valve in the steamsupply pipe, mechanism for automatically adjusting said valve, a vacuumpump for creating and maintaining a vacuum in the returns, a pluralityof vacuum controllers for the vacuum pump, connected to a return, asteam increase controller and a steam decrease controller, connected tosaid steam supply pipe, electric means, including mercoid switches,controlled by said steam increase and decrease controllers to operatesaid valve, and thermostats selectively connected to the increase anddecrease controllers to control the temperature as described.

9. In a vacuum steam heating system having steam supply means, radiationmeans, and return means therefor, a plurality of pressure control means,each for establishing and normally maintaining a predetermined pressurein the supply means, a plurality of pressure control means, each forestablishing and normally maintaining a different predetermined pressurein the return means, thereby providing for a plurality of pressuredifferentials between the supply and return means, the combination witha control mechanism comprising means to select the requisite pressurecontrol means in the supply means in accordance with temperatures in thearea to be heated, and means co-operative with said last means to selectthe requisite pressure control means in the return means, to vary thepressure diiferential between the supply and return means in accordancewith temperatures in the area being heated.

10. A control mechanism for a vacuum steam heating system having a steamsupply pipe, comprising a regulating valve in the steam supply pipe,automatically operable mechanism including steam increase and decreasecontrollers, connected to said supply pipe, electric means controlledthereby, for adjusting said valve to maintain in said system a higherpressure than required to heat the area to be heated, or a lowerpressure than so required, or to shut off the steam supply, thermostaticcontrol means for said antomatically operating mechanism for adjustingsaid valve, a vacuum pump for creating and maintaining a vacuum in thereturns, and a multi-stage controller means for the pump connectedautomatically to set the pump to create difierent degrees of vacuum inaccordancewith the d11- ierent pressures of steam, to produce variablepressure differentials for variable heat requirements in the area to beheated.

11. A vacuum steam heating system including a steam supply pipe, valvemeans for regulating the pressure in said supply pipe, selectively op-.erable high and low pressure controllers arranged to respond to pressurein said supply pipe, said controllers each being provided with switchesso arranged that when one is open the other is closed and vice versa, atleast one of the controllers comprising a casing, a pressure actuatablediaphragm arranged in the casing responsive to the pressure in thesupply pipe, a mechanical connection to the diaphragm and connectionsfrom said mechanical connection to the switches of said controllerarranged to eflect operation of said switches, electric means to selectand control the operation of a controller, and motorized means connectedto and controlled by the switches of the selected controller arranged toactuate said valve means so as to maintain in the system a pressurecorresponding to that of the controller selected.

12. A vacuum steam heating system including a steam supply pipe, valvemeans for regulating the pressure in said supply pipe, a combined,selectively operable steam increase controller means and decreasecontroller means arranged to respond to pressure in said supply pipe,said controller means comprising a casing, a pressure actuatablediaphragm arranged in the casing responsive to pressure in the supplypipe, a mechanical connection to said diaphragm, means cooperativetherewith to oppose motion oi! the diaphragm in one direction, othermeans cooperative therewith to oppose motion of the diaphragm in theopposite direction, said increase and decrease controller means eachbeing provided with pivoted mercoid switches, and connections from saidmechanical connection to said pivoted mercoid switches, electric meansto select and control the operation of a controller means, and motorizedmeans connected to and controlled by the switches of the selectedcontroller means arranged to actuate said valve means so as to maintainin the system a pressure corresponding to that of the controller meansselected.

13. A vacuum steam heating system including a steam supply pipe, valvemeans for regulating the pressure in said supply pipe, selectivelyoperable pressure controllers arranged to respond to different pressuresin said supply pipe, each of said controllers being provided with switchmeans, and at least one of said controllers comprising a casing, apressure actuatable diaphragm arranged in the casing responsive to thepressure in the supply pipe, a mechanical connection to the diaphragm,means opposing the motion of said diaphragm, and connections from saidmechanical connection to the switch means of said controller arranged toeffect operation of said switch means, thermostatic means to select andcontrol the operation oi! a controller to maintain a predeterminedpressure in the system, and motorized means connected to and controlledby the switch means of the selected controller arranged to actuate saidvalve means so as to maintain in the system a pressure corresponding tothat of the controller selected.

14. A vacuum steam heating system including a steam supply pipe, valvemeans for regulating the pressure in said supply pipe, selectivelyoperable steam increase and decrease controllers arranged to respond topressure in said supply pipe, each of said controllers being providedwith switch means, said controllers each comprising a casing, a pressureactuatable diaphragm arranged in the casing responsive to pressure inthe supply pipe, a mechanical connection to the diaphragm, meansopposing the motion of said diaphragm, the opposing means of onecontroller being. arranged to oppose the upward movement of thediaphragm, and the opposing means of the other controller being arrangedto oppose the downward movement of its diaphragm, and connections fromthe mechanical connection of each controller to the switch means of therespective controller arranged to eflect operation of said switch means,electric means to select and control the operation or a controller, andmotorized means connected to and controlled by the switches of theselected controller arranged to actuate said valve means so as tomaintain in the system a pressure corresponding to that of thecontroller selected.

15. A vacuum steam heating including a steam supply pipe, valve meansfor regulating the pressure in said supply pipe, a combined selectivelyoperable steamincrease controller means and decrease controller meansarranged to respond to pressure in said supply pipe, said combinedcontroller means comprising a casing, a pressure actuatable diaphragmarranged in the casing responsive to pressure in the supply pipe, amechanical connection to said diaphragm, means cooperative with saidmechanical connection for opposing the upward movement of the diaphragm,and means cooperative with said mechanical connection for opposing thedownward movement of the diaphragm, means for adjusting said mechanicalconnection, said increase and decrease controller means each beingprovided with pivoted mercoid switches, and connections from saidmechanical connection to said pivoted mercoid switches, thermostaticmeans to select and control the operation of a controller means tomaintain a predetermined pressure in the system, and motorized meansconnected to and controlled by the switches of the selected controllermeans arranged to actuate said valve means so as tomaintain in thesystem a pressure corresponding to that of the controller meansselected.

16. A vacuum steam heating system includin a steam supply pipe, valvemeans for regulating the pressure in said supply pipe, selectivelyoperable pressure controllers arranged to respond to different pressuresin said supply pipe, each of said controllers being provided with switchmeans, and at least one or said controllers comprising a casing, apressure actuatable diaphragm arranged in the casing responsive to thepressure in the supply pipe, a mechanical connection to the diaphragm,means opposing the motion of said diaphragm, and connections from saidmechanical connections to the switch means of said controller arrangedto effect operation of said switch means, thermostatic means to selectand control the operation of a controller to maintain a predeterminedpressure in the system, motorized means connected to andcontrolled bythe an electrical valve actuator adjacent the valve switch means of theselected controller arranged stem, gearing connecting said actuator tosaid. to actuate said valve means so as to maintain rack bar, andconnections between said actuator ,in the system a pressurecorresponding to that of and said switch means.

5 the controller selected, said motorized means comprising a valve stem,a rack on said stem, IRVING C. JENNINGS.

